Field of the Invention
This invention relates to the field of devices for protecting various types of control lines, such as hydraulic, electrical, and electronic control lines. Control lines are used, for example, in subsurface drilling operations and in the production activities of offshore oil and gas wells. In offshore operations, these lines extend from a control console located on the platform to valves, blowout preventers and other related devices located at or near a number of wellheads located around the platform.
The control lines are generally, but not always, strapped at intervals to the flow lines through which the oil and gas flows. Individual or multiple control lines are sheathed in a plastic-like material and the sheathed control line is attached to the flow line. In one form of the prior art, a single steel wire cable is encapsulated between two or more control lines, the wire cable having a diameter no greater than the control lines.
In offshore production areas, the flow lines and accompanying control lines leading from the well head to the platform are frequently subjected to impacts and forces caused by surface craft, floating debris and objects which sink to the ocean floor and contact the control lines. Consequently, the control lines are subject to impulse or impact and damaging forces applied thereto. The objects which create the impact or forces on the control lines are generally of such magnitude that the impact upon the control line can be represented by an impact plane acting upon the control lines. The impact line or force line therefore comes directly in contact with the enclosed hydraulic, electrical or electronic control lines subjecting these lines to damage. A continuous force such as an underwater rock and the like can constrict the reinforced plastic-like hydraulic lines thereby reducing their effectiveness in transmitting hydraulic fluid and forces which are transmitted from the platform to the well head in order to activate one or more values. Electrical and electronic control lines, when subjected to sharp impact or large forces are frequently severed and rendered inoperative.
Further shortcomings of existing control lines results from the splicing of the control lines. Whenever a break occurs in a flow line or in a control line, a splice is necessary. Most existing control lines consist of any number of hydraulic, electrical or electronic control lines cabled in relation to each other and encapsulated within a plastic-like jacket. If the distance between the platform and the well head is greater than the capacity of the control line bundle on the reel, it is necessary to splice additional control line length onto the original control line. Furthermore, if the control line is damaged, it is necessary to cut and splice the line around the damaged area. Because of the cabled configuration of most control lines, it is both difficult and time consuming to align the various encapsulated hydraulic, electrical and electronic lines and to splice the severed lines without a bulky support. In many cases, after the splice is accomplished, the control line is either equal in length to or effectively shorter than the other lines used with it. Consequently, any tension in the flow-line-control-line combination is somewhat borne by the control lines themselves.
Control line bundles generally consist of a first bundle containing hydraulic tubing and one or more additional bundles containing the desired electrical or electronic lines. Because hydraulic lines within the bundle are usually reinforced plastic-like lines, they are of a substantial cross-sectional area in order to obtain sufficient strength to contain the hydraulic pressure within. Moreover, because of their cabled configuration, the cross-sectional area of the hydraulic control line bundle is significant thereby reducing the length of the bundle placed on each reel. Thus, a number of reels and accompanying splices are required in order to complete the line from the platform to the underwater wellhead. The resulting weight, bulk, inconvenience in shipping and vast effort required in wrapping the control line bundle to the flow line and laying the combination under water is undesirable.
The most pertinent prior art of which the applicant is aware is an encapsulated control line described in U.S. Pat. No. 3,844,345 issued Oct. 29, 1974 to Evans. The device in the U.S. Pat. No. 3,844,345 is a substantial improvement over the above-described prior art in that the plurality of control tubes within the elastomeric material provides a reduction in the cross-sectional area of the encapsulated control line, and, when strapped to the flow line, generally conforms to the exterior cylindrical surface of the flow line. The applicant is further aware of a modification of the '345 device wherein a wire rope is embedded within the elastomeric material between the control lines. The modification to the '345 device, however, permits damage from impact and external forces on the encapsulated control tubes. In accordance with 37 C.F.R. 1.98(b), a copy of the foregoing patent is appended hereto.